FAQs

Below are our most frequently asked questions. Click a title to expand the response most relevant to your enquiry. If you have any further questions that are not answered in this FAQ, please contact us and we will be sure to get back to you shortly.

I'm installing a 450mm manhole cover over an inspection chamber and the depth is over 1.2m. What shall I do?

Use the CLKS 499 Reducer. This fits under all our polypropylene 450mm diameter inspection covers and will reduce the clear opening to 350mm, thus complying with building regulations.

How do I know what size manhole cover I need?

All manhole cover sizes are measured by the clear opening inside the frame as this is the only true constant between manufacturer's designs.

I'm fitting a cover on a 450mm inspection chamber in my driveway/garden and do not know which one to use. Can you advise?

We recommend using our CLKS 452 Polypropylene cover & frame, which complies with Doc H of the Building Regulations 2002.

Do forklifts require a different loading class to vehicles fitted with pneumatic tyres?

Calculations show that they apply at least 4 times the load of a 10 Tonne lorry, along with extra dynamic forces due to solid tyres, limited suspension etc.

Clark-Drain recommends the use of our forklift rated covers for use in all forklift loading areas.

What products should I install in a driveway?

Clark-Drain recommends B125 covers as a minimum specification for driveway use. A15 covers are for use in pedestrian areas only and should not be used in driveways. Further detailed advice can be found in our catalogues.

The pavior cover I had installed a while ago is bowing. Why is this?

This might happen if our installation guidelines have not been followed and the block paviors surrounding the frame were laid on sand only rather than mortar. In this scenario, it is possible for the sand under the paviors and around the frame to work loose, thus reducing support and potentially allowing the cover and frame to bow. Provided the problem is addressed early enough, and assuming that no abnormally heavy vehicles have driven over the cover, it should be possible to effect a repair. Remove the blocks and the cover & frame and reinstall them all on a bed of weak-mix mortar.

Refer to our installation guides for further information.

What purpose does the protective coating on my cast iron manhole cover serve?

The bitumen-based coating on all our cast iron manhole covers, gully gratings and channel gratings provides temporary protection from the elements for the period between manufacture and installation. The coating will wear off through normal traffic use. This will not affect the strength and performance of the product.

How do I lift a cover that is fitted with integral keys?

Remove the dust cap marked 'KEY UNDER CAP' by gently prising it up from both ends. Lift the key out by using the recessed finger slots half way along each side and raise it vertically. Grasp keys firmly and carefully lift the lid out. Always use all the keys that are fitted to the cover when lifting (Most covers have two keys but some have 4).

I have manhole covers in my garden that I would like to conceal. Do you have a product that can help?

The Chameleon (Product code CD 470) is the ideal solution for manhole covers in gardens, soft landsacpes and borders. The Chameleon enables you to infill to a depth of 100mm to ensure your grass keeps growing in all of the inset. Simply remove your cast iron or polypropylene cover, drop the chameleon into the exisiting frame and fill with bark, turf, soil and grass seed, chippings, gravel, plants, etc.